1. Field of the Disclosure
The instant disclosure relates to an auto-mute control circuit; in particular, to an auto-mute control circuit applied into an analog input amplifier.
2. Description of Related Art
A concept of auto-mute is broadly used in reducing noise of a data converter when all of inputs are zero during a data converting process, and a Digital-to-Analog Converter (DAC) is one of examples. During a process of a digital signal being converted into an analog signal, there are some techniques, such as a Dithering, to improve a quantization error. However, when there is no input signal, the Dithering causes the DAC outputting the noise. There are many automatic mute technology practiced in digital way, and it becomes easier to determine what is the so-called “zero-input” because signals are quantized and digitized.
However, there is still a need of auto mute for the analog input amplifier to further reduce the noise outputted. In an analog circuit, a key to make an auto mute function work is how to detect the so called “zero-input.” The “zero-input” in the analog circuit field indicates that an input signal is lower than a level for a specific amount and thus it is omitted and seen as the “zero-input.” Therefore, in the analog circuit field, a possible challenge is how to detect a very small amplitude signal.